From field to landscape scale: collective management of phytophagous insects in arable farming within the R2D2 project.

In conventional agriculture, insecticide applications remain a predominant component in pest management strategies. However, increasing societal concerns regarding environmental protection, biodiversity preservation, the widespread phenomenon of resistance, and global changes underscore the urgent need for a paradigm shift. Combining cultivation techniques can contribute to significantly reduce insecticide use but is insufficient for their complete elimination. The R2D2 project, which engages 10 farmers cultivating 1300 hectares of field crops on the "plateaux de Bourgogne", introduces an innovative approach by laying the groundwork for coordinated management of phytophagous insects at the territorial level. This approach combines cultivation techniques and agronomic practices with the principles of conservation biological control. Through a collaborative effort, R2D2 aims to co-design and implement a collective agroecological pest management strategy, enabling farmers to progressively reduce their reliance on insecticides. After five years, the project has driven substantial changes in farming practices and pest management strategies, particularly in oilseed rape cultivation, which has been severely impacted by insects resistant to pyrethroid insecticides. Collective actions have been initiated to enhance biological regulations at the territorial level and to reduce cabbage stem flea beetle populations through behavioural manipulation techniques. Additionally, farmers have adopted agronomic measures to improve oilseed rape resilience. Consequently, oilseed rape cultivated areas have expanded significantly, yields have increased and stabilized, and insect management strategies have shifted towards a more thoughtful application of insecticides. Despite the progress in oilseed rape cultivation, further efforts are required to reduce the insecticide treatment frequency index (TFI) for peas and spring barley, which also face considerable pest challenges and require alternative solutions. Finally, continued long-term support and the search for financial means to encourage risk-taking will likely be necessary to enable farmers to profoundly change their cropping systems and landscape structure to make them more favourable to biological regulations.